Communications systems and method of transmitting information

ABSTRACT

Media access control in known communications systems relies upon an initial position of a mobile terminal and one or more Quality of Service parameters. In order to improve the quality of allocation of resources, the present invention provides a communications system and a method therefor for allocating resources in response to the mobile terminal ( 110 ) following a predicted path ( 113 ) to an optimum location ( 116 ) where the radio environment is better than the radio environment at the initial location ( 112 ).

BACKGROUND TO THE INVENTION

The present invention relates to mobile communication systems andparticularly to communication of information from one communicationsdevice to another, the information having a time period associatedtherewith corresponding to a tolerable delay associated withtransmission of the information.

SUMMARY OF THE PRIOR ART

The Universal Mobile Telecommunications System (UMTS) currently understandardisation will support a combination of different service typesand data rates for the transmission of information. Distinctcommunication channels are defined by separation of codes used by aWideband-Code Division Multiple Access (W-CDMA) scheme and/or a TimeDivision-Code Division Multiple Access (TD-CDMA) scheme employed by theUMTS. A UMTS network comprises a plurality of base stations referred toas Node Bs, each Node B supporting a respective cell. Capacity withinthe each respective cell is interference limited and so as the number ofusers increases in a given cell, interference levels increase as well.In order to balance needs of a particular user against needs of otherusers supported in the given cell, Medium Access Control (MAC) isprovided to manage allocation of resources (channels), i.e. balanceaggregate capacity against individual user capacity.

Some known MAC algorithms take into account acceptable delay associatedwith a service and Quality of Service (QoS) parameters of a call inorder to determine when to release a resource, the release of theresource being based on a number of factors, for example cell loading,call priority, or prevailing radio conditions. “Channel AllocationSchemes for Cellular Mobile Telecommunications: A Comprehensive Survey”by I Katzela and M Naghshneh (IEEE Personal Communications, June 1996pages 10–31) describes use of a current location of a mobile terminal inconjunction with QoS parameters in order to determine when to releasethe resource. However, if the mobile terminal is moving, an optimuminstant for releasing the resource may no longer be the optimum instant,because a radio environment in which the mobile terminal is locatedvaries as the mobile terminal moves.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided amethod of transmitting information between a mobile terminal and acommunications device, the information having a time period associatedtherewith corresponding to a tolerable delay associated withtransmission of the information, the method comprising the steps of:making a prediction of subsequent locations of the mobile terminal towhich the mobile terminal is anticipated to move from a previouslocation during the time period; determining whether a subsequentlocation is an optimum location for transmitting the information betweenthe mobile terminal and the communication device, and withholding anallocation of a resource for transmitting the information between themobile terminal and the communications device until the mobile terminalreaches the optimum location.

Hence, release of resources for transmission of the information can bewithheld until the mobile terminal has reached an optimum locationhaving a favourable environment for the reception and/or transmission ofdata.

If it is predicted that the mobile terminal will never reach the optimumlocation, then the resources are released at any time within thetolerable delay period.

If it is predicted that the mobile station is heading for a locationhaving a less favourable environment then the one it is already in, thenthe resources are released without delay.

The step of predicting a subsequent location may comprise the use ofDoppler shift measurements, pathloss measurements, a global positioningsystem and/or maps.

The optimum location may be defined as being a radio environment havingat least one optimum quality of service parameter.

The communication device may be a base station or “Node B” forming partof a mobile communications system. The base station may be fixed orsupported on a moving or moveable platform, eg satellite.

The method may further comprise the steps of: predicting a subsequentlocation of the communications device, and allocating the resource inresponse to the mobile terminal being at the optimum location as aresult, at least in part, of movement of the communications device.

According to a second aspect of the present invention, there is provideda resource controller, the resource controller being arranged todetermine a first location of a mobile terminal and predict subsequentlocations of the mobile terminal to which the mobile terminal isanticipated to move from the first location during a time periodcorresponding to a tolerable delay associated with transmission ofinformation between the mobile terminal and a communication device;wherein the resource controller is arranged to withhold an allocation ofa resource for transmitting the information between the mobile terminaland the communications device until the mobile terminal reaches theoptimum location prediction.

The present invention also provides a computer program productcomprising a medium on or in which is recorded a program, which, whenexecuted in a computer-controlled system will perform any of the methodsrecited herein.

It is thus possible to provide a method and system, with improvedresource allocation ability, for transmitting information betweendevices. Additionally, the method can be easily incorporated intoexisting systems in the form of an upgrade. The information cantherefore be transmitted at an optimum opportunity during the timeperiod associated with the information, thereby improving the likelihoodof accurate receipt of the information.

BRIEF DESCRIPTION OF THE DRAWINGS

At least one embodiment of the invention will now be described, by wayof example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a communications system constituting anembodiment of the present invention, and

FIG. 2 is a flow diagram of a method for use with the system of FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Throughout the description, like parts will be identified by identicalreference numerals.

Referring to FIG. 1, a UMTS network 100 comprises a core network 102operably coupled to a Radio Network Controller (RNC) 104, the RNC 104being coupled to a first Node B 106 and a second Node B 108. A mobileterminal 110 is situated at an initial location 112 and is capable ofcommunicating with the first Node B 106.

The above communication system will now be described in the context ofthe mobile terminal 110 following an actual path starting from theinitial location 112 having an initial radio environment associatedtherewith.

In operation (FIG. 2), the mobile terminal 110 requests transmission ofdata to the core network 102 for onward routing (step 200).Alternatively, the core network 102 can request transmission of data tothe mobile terminal 110, the data being received by the core network 102from another mobile terminal (not shown) or another host entity (notshown) capable of communicating data through the core network 102 forreceipt by the mobile terminal 110.

The RNC 104 supports a MAC algorithm, the MAC algorithm determining(step 202) a period of time corresponding to an acceptable time delayfor the communication of the data between the first Node B 106 and themobile terminal 110. Additionally, other QoS parameters can beascertained by the MAC algorithm, for example, by association orencapsulation with the request to transmit data (step 200). Examples ofthe other QoS parameters are: a peak data rate or a tolerable Bit ErrorRate (BER) associated with the communication of the data between thefirst Node B 106 and the mobile terminal 110.

The MAC algorithm then estimates (step 204) the initial location 112 ofthe mobile terminal 110 and predicts a path 113 being followed by themobile terminal 110 using one or more radio parameter corresponding to alocation and/or direction, for example Doppler shift, path loss, anEnhanced Observed Time Difference technique, or a Global PositioningSatellite (GPS) signal.

The MAC algorithm then determines (step 206) whether any point along thepredicted path 113 predicted by the MAC algorithm is an optimum location116. The optimum location corresponds, for example, to a location havingan improved radio environment over the initial radio environment at theinitial location 112. If a point on the predicted path 113 correspondsto the optimum location 116, the MAC algorithm determines (step 208)whether the mobile terminal 110 has reached the optimum location,assuming that the mobile terminal follows the predicted path 113. If themobile terminal has not reached the optimum location 116, the MACalgorithm re-calculates the predicted path 113 during the time periodand re-determines (step 206) whether any point on the predicted path 113corresponds to the optimum location 116. The steps of re-calculating thepredicted path 113 and determining whether any point on the predictedpath corresponds to an optimum location (steps 204, 206) are repeateduntil either the mobile terminal 110 reaches the optimum location 116 orthe MAC algorithm determines that there are no points along thepredicted path 113 that corresponds to the optimum location 116. If thepredicted path 113 does not comprise any points corresponding to theoptimum location 116, the MAC algorithm allocates (step 210) a resource(channel) for communicating the data between the mobile terminal 110 andthe first or second Node B 106, 108.

However, if the mobile terminal 110, whilst travelling along the actualpath, reaches the optimum location 116, the MAC algorithm allocates(step 210) the resource for communicating the data. In this example, themobile terminal 110 is better supported by the second Node B 108 thanthe first Node B 106 when located at the optimum location, the optimumlocation being optimum by virtue of the proximity of the second Node B108 to the mobile terminal 110.

In order to assist the MAC algorithm, an electronic map can be used inorder to enhance generation of the predicted path 113, for example, themap can be used to resolve a choice of two possible predicted paths, themap enabling one of the possible predicted paths to be discounted.

Although the above example describes the MAC algorithm being supportedby the RNC 104, it should be appreciated that the MAC algorithm can besupported by an intelligent network element, for example, the corenetwork 102, the mobile terminal 110 or any other part of the UMTSnetwork 100 (or any other communications network) capable of monitoringcommunications traffic in a cell/sector supported by the first and/orsecond Node B 106, 108.

Additionally, it is envisaged that some or all of the functionality ofthe first and/or second Node B 106, 108 can be performed by a furthermobile terminal (not shown). Consequently, the RNC 104 (or otherintelligent network entity) can determine the optimum location withrespect to the further mobile terminal (not shown) when the furthermobile terminal performs some or all of the functionality of the firstand/or second Node B 106, 108.

1. A method of transmitting information between a mobile terminal and acommunications device, the information having a time period associatedtherewith corresponding to a tolerable delay for the transmission of theinformation, the method comprising the steps of: associating a qualityof service (QoS) parameter with a request to transfer information,determining a time period corresponding to an acceptable time delay forthe communication of the information, making a prediction of subsequentlocations of the mobile terminal to which the mobile terminal isanticipated to move from a previous location during the time period,determining whether a subsequent location is an optimum location withrespect to the specified QoS parameter for transmitting the informationbetween the mobile terminal and the communications device, andwithholding an allocation of a resource for transmitting the informationbetween the mobile terminal and the communications device until themobile terminal reaches the optimum location before the acceptable timedelay.
 2. A method as claimed in claim 1, further comprising the stepof: allocating the resource when the mobile terminal reaches the optimumlocation.
 3. A method as claimed in claim 1, further comprising the stepof: allocating the resource before the expiry of the time period if itis predicted that any subsequent location is not an optimum location. 4.A method as claimed in claim 1, further comprising the step ofallocating the resource without delay if it is predicted that there is adegradation in subsequent locations.
 5. A method as claimed in claim 4,wherein if the mobile terminal has not reached the optimum location,further comprising the steps of: re-calculating the predicted pathduring the time period, and re-determining whether any point on thepredicted path corresponds to the optimum location.
 6. A method asclaimed in claim 1, further comprising the steps of: predicting asubsequent location of the communications device, and allocating theresource in response to the mobile terminal being at the optimumlocation as a result, at least in part, of movement of thecommunications device.
 7. A resource controller, the resource controllerbeing arranged to associate a quality of service (QoS) parameter with arequest to transfer information, determining a time period correspondingto an acceptable time delay for communication of the information,determine a first location of a mobile terminal and predict subsequentlocations of the mobile terminal to which the mobile terminal isanticipated to move from the first location during the time periodcorresponding to a tolerable delay for the transmission of informationbetween the mobile terminal a communications device, determining whethera subsequent location is an optimum location with respect to thespecified QoS parameter for transmitting the information between themobile terminal and the communications device, wherein the resourcecontroller is arranged to withhold an allocation of a resource fortransmitting the information between the mobile terminal and thecommunications device until the mobile terminal reaches the optimumlocation before the acceptable time delay.